Paper-feeding mechanism

ABSTRACT

The paper-feeding mechanism includes a duplex drive roller disposed on a terminal end of a feeding path of an image-forming device for feeding paper and on a side of an output tray, a first idle roller for conveying the paper back to the output tray with the duplex drive roller after a single side of the paper is printed, a second idle roller for conveying the paper back to the output tray with the duplex drive roller after double sides of the paper are printed, and a stop means installed between the terminal end of the feeding path and the output tray for switching to a shut position to stop the paper when the paper is driven back to the feeding path and for switching to an open position when the paper is driven to the output tray after the double sides of the paper are printed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a paper-feeding mechanism, and more particularly, to a paper-feeding mechanism capable of preventing paper from entering to a nip between a duplex drive roller and an idle roller incorrectly.

2. Description of the Prior Art

Image-forming devices with a duplex feeding function are widely used due to efficient utilization and cost down of paper. Please refer to FIG. 1 and FIG. 2. FIG. 1 is a diagram of conveying paper S to an output tray 5 in a duplex feeding mode in the prior art. FIG. 2 is a diagram of conveying back the paper S in the duplex feeding mode in the prior art. The paper S is drawn out piece by piece along a feeding path to an image-forming section. After imaging the paper S, the paper S is conveyed from a terminal end of the feeding path to the output tray 5. Please refer to FIG. 1, a duplex drive roller 22 and a first idle roller 33 drive the paper S with a single printed side to the output tray 5, and a leading edge of the paper S falls on a paper stack 13 on the output tray 5. Please refer to FIG. 2. Then the duplex drive roller 2 rotates reversely and drives the paper S with the first idle roller 33 back to the feeding path so as to print the other side of the paper S. At this time, the previous leading edge converts into a trailing edge of the paper S. There is frictional force between the paper S and the paper stack 13 on the output tray 5 because the paper S contacts with the paper stack 13 so that it is possible that the frictional force draws the paper S to a nip between the duplex drive roller 22 and a second idle roller 44 incorrectly resulting in a paper jam.

SUMMARY OF THE INVENTION

It is therefore a primary objective of the claimed invention to provide a paper-feeding mechanism capable of preventing paper from entering to a nip between a duplex drive roller and an idle roller incorrectly for solving the above-mentioned problem.

According to the claimed invention, the paper-feeding mechanism utilized for an image-forming device includes a duplex drive roller disposed on a terminal end of a feeding path of the image-forming device for feeding paper and on a side of an output tray, a first idle roller for conveying the paper back to the output tray with the duplex drive roller after a single side of the paper is printed, a second idle roller for conveying the paper back to the output tray with the duplex drive roller after double sides of the paper are printed, and a stop means installed between the terminal end of the feeding path and the output tray for switching to a shut position to stop the paper when the paper is driven back to the feeding path and for switching to an open position not to stop the paper when the paper is driven to the output tray after the double sides of the paper are printed.

These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of conveying paper to an output tray in a duplex feeding mode in the prior art.

FIG. 2 is a diagram of conveying back the paper in the duplex feeding mode in the prior art.

FIG. 3 is a perspective drawing of a paper-feeding mechanism utilized for an image-forming device according to a preferred embodiment of the present invention.

FIG. 4 is a diagram of paper conveying to an output tray after a single side of the paper is printed in a duplex feeding mode according to the preferred embodiment of the present invention.

FIG. 5 is a diagram of the paper conveying back for printing the other side of the paper in the duplex feeding mode according to the preferred embodiment of the present invention.

FIG. 6 is a diagram of the paper conveying out of a feeding path after printing double sides of the paper in the duplex feeding mode according to the preferred embodiment of the present invention.

FIG. 7 is a diagram of the paper conveying to the output tray after printing the double sides of the paper in the duplex feeding mode according to the preferred embodiment of the present invention.

FIG. 8 is a perspective drawing of a paper-feeding mechanism utilized for an image-forming device according to another preferred embodiment of the present invention.

DETAILED DESCRIPTION

Please refer to FIG. 3 to FIG. 7. FIG. 3 is a perspective drawing of a paper-feeding mechanism utilized for an image-forming device according to a preferred embodiment of the present invention. FIG. 4 is a diagram of paper conveying to an output tray 5 after a single side of the paper is printed in a duplex feeding mode according to the preferred embodiment of the present invention. FIG. 5 is a diagram of the paper conveying back for printing the other side of the paper in the duplex feeding mode according to the preferred embodiment of the present invention. FIG. 6 is a diagram of the paper conveying out of a feeding path after printing double sides of the paper in the duplex feeding mode according to the preferred embodiment of the present invention. FIG. 7 is a diagram of the paper conveying to the output tray 5 after printing the double sides of the paper in the duplex feeding mode according to the preferred embodiment of the present invention. The paper-feeding mechanism is utilized for the image-forming device with the duplex feeding function, such a scanner, a multifunction product, a printer with a duplex printing function, and so on. The paper-feeding mechanism is disposed on a terminal end of the feeding path of the image-forming device. Please refer to FIG. 3, a drive shaft 7 is connected to a frame on lateral sides of the terminal end of the feeding path of the image-forming device and is driven by a motor (not shown in figures). A duplex drive roller 22 is installed on the drive shaft 7. A first idle roller 33 and a second idle roller 44 are disposed on an upper side and a bottom side of the duplex drive roller 22 respectively, and the first idle roller 33 and the second idle roller 44 cooperate with the duplex drive roller 22. When the duplex drive roller 22 rotates forward, the duplex drive roller 22 and the first idle roller 33 drive the paper with a single printed side to a print an image-forming section. When the duplex drive roller 22 rotates backward, the duplex drive roller 22 and the first idle roller 33 drive the paper with the single printed side to the feeding path again.

A hole 61 is disposed below the second idle roller 44 on the frame nearby the terminal end of the feeding path. There are two stop means 6 disposed on both sides of the second idle roller 44 and between the terminal end of the feeding path and the output tray 5. The stop means 6 is connected to a shaft 62. The stop means 6 includes a connecting part 68 fixed on the shaft 62, a top part 66, and an arched part 69 formed between the connecting part 68 and the top part 66. An arched cavity of the arched part 69 is disposed opposite to an exit direction of the paper. The stop means 6 can be paired to dispose preferredly.

The shaft 62 connected to the stop means 6 is pivoted inside the hole 61 in a rotatable manner. When the paper is not conveyed from the nip between the duplex drive roller 22 and the second idle roller 44, the stop means 6 is switched to a shut position. When the paper is conveyed from the nip between the duplex drive roller 22 and the second idle roller 44, the stop means 6 rotates around the shaft 62 to be switched from the shut position to an open position so as to convey the paper to the output tray 5.

Please refer to FIG. 3. A torsional spring 63 is sheathed on the shaft 62 for turning the stop means 6 from the open position to the shut position. The torsional spring 63 includes a fixing part 631 wedged inside a cavity 641 of a casing 64, and a pushing part 632 contacting against a face neighboring to the output tray 5 of the stop means 6. When the paper passes the nip between the duplex drive roller 22 and the second idle roller 44, the leading edge of the paper pushes the stop means 6 from the shut position to the open position so as to convey the paper to the output tray 5. At this time, the pushing part 632 of the torsional spring 63 is pressed down. After the paper has been conveyed to the output tray 5 completely, the restoring force of the torsional spring 63 drives the pushing part 632 to an original position so that the stop means 6 restores to the shut position.

There is frictional force between paper S and the paper stack 13 on the output tray 5 because the paper S contacts with the paper stack 13 so that it is possible that the frictional force draws the paper S to the nip between the duplex drive roller 22 and the second idle roller 44 incorrectly resulting in a paper jam. Please refer to FIG. 4. The duplex drive roller 22 and the first idle roller 33 drive the paper with one printed side along the feeding path (not shown in figures) to the output tray 5 in a duplex feeding mode. The leading edge of the paper S falls on the paper stack 13 but the paper S has not been conveyed to the output tray 5 completely after the paper S moves at a certain distance. For printing the other side of the paper S, the duplex drive roller 22 rotates reversely and drives the paper S back to the feeding path with the first idle roller 33. At this time, the previous leading edge converts into a trailing edge of the paper S. It is possible that the frictional force between the paper S and the paper stack 13 draws the paper S to the nip between the duplex drive roller 22 and the second idle roller 44 incorrectly.

Please refer to FIG. 5. The stop means 6 between the terminal end of the feeding path and the output tray 5 is located in the shut position and in front of the nip between the duplex drive roller 22 and the second idle roller 44. The leading edge of the paper S drawn to the nip between the duplex drive roller 22 and the second idle roller 44 incorrectly will be blocked by the stop means 6 and can not enter to the nip between the duplex drive roller 22 and the second idle roller 44 for preventing the paper jam.

Please refer to FIG. 6. After the double sides of the paper S have been printed, the duplex drive roller 22 and the second idle roller 44 drive the paper S to the output tray 5. When the paper S passes the nip between the duplex drive roller 22 and the second idle roller 44, the leading edge of the paper S pushes the stop means 6 from the shut position to the open position so as to convey the paper S to the output tray 5 smoothly. At this time, the pushing part 632 of the torsional spring 63 is pressed down by the stop means 6 in the open situation.

Please refer to FIG. 7. After the paper S has been conveyed to the output tray completely, the paper S can not apply force to the stop means 6 and the restoring force of the torsional spring 63 drives the pushing part 632 to the shut position so that the stop means 6 is capable of preventing the next paper from entering to the nip between the duplex drive roller 22 and the second idle roller 44 incorrectly.

Please refer to FIG. 8. FIG. 8 is a perspective drawing of a paper-feeding mechanism utilized for an image-forming device according to another preferred embodiment of the present invention. The difference between the above-mentioned embodiment and this embodiment is that a weight stack 67 is to substitute the torsional spring 63 as a restoring means. The weight stack 67 is connected to an end of the shaft 62. The weight stack 67 and the shaft 62 can be integrated preferredly. When the paper S passes the nip between the duplex drive roller 22 and the second idle roller 44, the leading edge of the paper S pushes the stop means 6 from the shut position to the open position so as to convey the paper S to the output tray 5 smoothly. At this time, the weight stack 67 connected to the end of the shaft 62 rises. After the paper S has been conveyed to the output tray 5 completely, the paper S can not apply force to the stop means 6 and the weight stack 67 goes down by the gravity thereof so that the stop means 6 restores to the shut position for preventing the next paper from entering to the nip between the duplex drive roller 22 and the second idle roller 44 incorrectly.

In contrast to the prior art, the present invention provides the restoring means to block the paper in front the nip between the duplex drive roller and the second idle roller when the frictional force between the paper and the paper stack draws the paper to the nip between the duplex drive roller and the second idle roller incorrectly so as to prevent the paper jam effectively.

Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. 

1. The paper-feeding mechanism utilized for an image-forming device comprising: a duplex drive roller disposed on a terminal end of a feeding path of the image-forming device and disposed on a side of an output tray for feeding paper; a first idle roller for conveying the paper to the output tray with the duplex drive roller after a single side of the paper is printed; a second idle roller for conveying the paper to the output tray with the duplex drive roller after double sides of the paper are printed; and a stop means installed between the terminal end of the feeding path and the output tray for switching to a shut position to stop the paper when the paper is driven back to the feeding path and for switching to an open position not to stop the paper when the paper is driven to the output tray after the double sides of the paper are printed.
 2. The paper-feeding mechanism of claim 1 wherein the stop means is pivoted on the terminal end of the feeding path.
 3. The paper-feeding mechanism of claim 1 further comprising a restoring means connected to the stop means for turning the stop means from the open position to the shut position.
 4. The paper-feeding mechanism of claim 2 further comprising a shaft connected to the stop means and pivoted to the image-forming device for driving the stop means to rotate.
 5. The paper-feeding mechanism of claim 3 wherein the restoring means is a torsional spring.
 6. The paper-feeding mechanism of claim 5 wherein the torsional spring comprises: a pushing part contacting against the stop means; and a fixing part fixed on the image-forming device.
 7. The paper-feeding mechanism of claim 3 wherein the restoring means is a weight stack.
 8. The paper-feeding mechanism of claim 7 further comprising a shaft connected to the stop means and pivoted to the image-forming device for driving the stop means to rotate wherein the weight stack is connected to an end of the shaft.
 9. The paper-feeding mechanism of claim 1 wherein the stop means comprises an arched part and an arched cavity of the arched part is disposed opposite to an exit direction of the paper. 